1. Field of the Invention
The invention relates to a system and a method for continuously manufacturing a liquid crystal display panel and to an inspection; apparatus and an inspection method.
2. Description of the Related Art
Japanese Patent Application Laid-Open (JP-A) No. 2010-170126 discloses a method and a system for manufacturing a liquid crystal display panel by a process including the steps of laminating polarizing films on both the front and back surfaces of a liquid crystal cell to form a liquid crystal display panel and optically inspecting the liquid crystal display panel. Specifically, the disclosed inspecting step includes perpendicularly applying light to the lower surface of the liquid crystal display panel from a light source, imaging the transmitted light to obtain image data, and subjecting the obtained image data to image analysis to determine the presence or absence of a defect so that it can be determined whether the product is non-defective or defective.
Patent document 1: Japanese Patent Application Laid-Open JP-A No. 2010-170126.
Unfortunately, the disclosure in Japanese Patent Application Laid-Open (JP-A) No. 2010-170126 has a problem in which foreign bodies contained in a liquid crystal display panel cannot be easily detected. The reason is as follows. If a foreign body exists between a liquid crystal cell and a polarizing plate, only part of the polarizing plate where the foreign body exits should be deformed and undergo the cancellation of the crossed Nicols state so that only the part should form a white image due to light leakage. Actually, however, when a light source and a camera are placed opposite to each other, as shown in FIGS. 7A and 7B, not only the light generated by the cancellation of the crossed Nicols state but also light refracted, scattered, or reflected by the foreign body enter the camera. As a result, the noise increases around the foreign body (the contrast decreases) so that the outline of the foreign body is blurred, which causes a problem in which the foreign body cannot be easily detected (the inspection precision decreases).